On the other hand, Cdk5 is also generally dysregulated in various cancer cells (Liu et al, 2017; Sharma and Sicinski, 2020; Shupp et al, 2017; Pozo and Bibb, 2016), and, importantly, the Rb protein is a downstream target of Cdk5 in neuroendocrine thyroid cancer (Pozo et al, 2013). This evidence concerns the gene RB1 and cancer.